The invention relates to the field of the transport or distribution of perishable foodstuffs and other pre-cooked dishes or foods, in isothermal containers, be they for example container crates or lorries, where the cold chain is maintained by the intervention of a chilling fluid (cold gas, cryogenic liquid such as liquid nitrogen, dry ice, etc.).
Thus by way of example, central kitchens or distribution centers use isothermal trolleys to transport and distribute pre-cooked dishes or foods from their kitchens or facilities to the places of consumption: hospital catering, company or school restaurants, etc., etc.
The very numerous configurations of containers and of types of cooling which are available on the market will not be exhaustively detailed here, in particular the isothermal container/trolley types, with or without demarcated cryogenic compartment, with or without a reservoir (“cassette”) comprising the cold fluid to be inserted into the container, etc.
Likewise, the chilling fluid (gas, cryogenic liquid, solid, be it nitrogen, CO2 or other, etc.) can be deposited directly in the container, or in a reservoir to be inserted into the container, or sent to an exchanger situated in the container, or else, still by way of illustration, sent to a holder, situated in the container itself or in proximity (or else adjoining, for example when the container is a lorry), from which holder fluid is tapped off so as to send it to the container, to a reservoir situated in the container, to an exchanger situated in the container, etc., etc.
It is seen on reading the foregoing that the situations and configurations are extremely varied.
By way of illustration it may nevertheless be pointed out that cryogenic trolleys/containers are typically of parallelepipedal form and very often comprise a cryogenic compartment disposed in the upper part of the container, above the storage compartment wherein are disposed the products having to be preserved at controlled temperature, and traditionally, this upper compartment receives a reservoir intended to contain a refrigerating product, for example carbon dioxide in the solid phase, whose sublimation releases cold gases, compensating for the entry of heat through the seals between the container and its door or else through the insulant of the container. The pre-cooked dishes (or other perishable products) are then housed in the product storage compartment of these isothermal containers, which are themselves transported in lorries to the user site (hospital, school canteen, etc.).
It is well known that the regulations in force relating to compliance with the cold chain when transporting perishable foodstuffs are becoming increasingly rigorous, and are causing in particular those involved in such food distribution to evolve in terms of preparation and traceability of the products to be transported.
In practice, it is noted that the operator charged with injecting the fluid into each container, for example into each container crate, performs it in a relatively empirical manner, at best as a function of a certain number of pre-established “recipes” (buttons at the level of the injection cabinet that he actuates allowing the implementation of different and predetermined durations of injection).
Now, experience shows that the quantity of fluid required in each case depends on numerous factors which are not currently taken into account sufficiently well, and which are related in particular to the container's journey between its loading and its final place of use (“logistic” journey).
It is then appreciated that approximate procedures such as these will be less and less compatible with the growing demands of the new regulations which ask for much more rigorous control and tracking of the temperatures the whole way along the journey of such containers, or indeed of each container.